As a container for holding a liquid material such as a cosmetic solution, a chemical, and drinking water, a container with a cap having an excellent corrosion resistance and a satisfactory airtight property has been widely used. The container is generally made of a glass. In some cases, a metal container can also be used to obtain similar effects.
The glass container has a dignity sense and a high quality sense, thereby being suitably used for a container of a cosmetic solution in particular. However, in some cases, the glass container may be easily damaged by a shock during a carrying operation or by a drop in use.
On the other hand, the metal container has an excellent shock resistance in particular. However, a weight and a raw material cost thereof are increased, and a processing thereof has a lot of trouble.
In many cases, the glass container and metal container are in a simple shape, thereby being lacking in a decorating property.
As shown in FIG. 10, Patent document 1 proposes a composite container 104 in which a resin is over-molded on a container 100 made of a glass or a metal to form a resin sheathing body 102 outside the container 100 in order to add a design property.
On the other hand, in the case in which the container is made of a synthetic resin, the container is manufactured by a method such as a blow molding method and a method of forming two divided molding bodies in advance and of welding the two bodies using a vibration welding method, thereby reducing a manufacturing cost and enabling a mass production.
However, the blow molding method just enables a formation of only a thin-walled container. Consequently, a shape of the container is restricted to a certain degree, thereby being lacking in a decorating property in some cases.
Moreover, the method of welding the two divided molding bodies using a vibration welding method enables a manufacture of a container in a free shape as compared with the blow molding method. However, in the case in which a liquid material to be held in the container is a chemical or the like, a material of the container is restricted to a costly resin having an excellent chemical resistance, thereby increasing a resin cost disadvantageously.
As a method to solve the above problems, Patent document 2 discloses a synthetic resin hollow body 206 as shown in FIG. 11. To form the synthetic resin hollow body 206, an inner shell 200 is formed at first by combining divided molding bodies or by a blow molding method. A molten resin made of a material equivalent to or other than that of the inner shell 200 is then injected outside the inner shell to form an over-molded portion 202, thereby integrating the over-molded portion 202 with the inner shell 200.
Such a synthetic resin hollow body 206 has a two-layer structure, thereby further improving a decorating property. Moreover, a resin having an excellent chemical resistance can be used for only the inner shell 200, and a comparatively low cost resin can be used outside the inner shell, thereby reducing a total resin cost for the synthetic resin hollow body 206.    Patent document 1: Japanese Unexamined Patent Application Publication No. 2004-527424    Patent document 2: Japanese Patent Application Laid-Open Publication No. 06-23758